1. Field of the Invention
This disclosure relates to systems and methods for disposing of contaminated equipment and supplies, in particular to a lined storage bin which vents air trapped by a liner bag to the environment.
2. Description of the Related Art
Sanitation and sterilization are important to preventing infection and disease in medical practice, particularly in the typical environment where a medical facility and its equipment are used to treat a series of patients. Each treatment may result in the generation of medically contaminated materials ranging from tongue depressors and plastic thermometer covers to surgical towel, gloves, and smocks soiled with bodily fluids from a patient undergoing emergency surgery in an operating room. These materials pose a risk of disease and infection to both the attending staff and future patients treated in the same facility using the same equipment, and both the treatment rooms and equipment are normally sterilized and sanitized before the next patient is treated.
To this end, soiled or potentially contaminated equipment is generally sequestered in disposal bins specially marked as containing contaminated materials. These materials may be items that are intended to be used once on a single patient and then permanently discarded, or equipment that may be sterilized and used again on a subsequent patient. Ideally, after treatment concludes, the treatment room is cleaned and sterilized, and the bag lining the disposal bin is sealed and safely discarded, and a new bag is placed in the disposal bin.
In many contexts, particularly the fast-paced environment of an emergency department or a delicate surgical operation, the doctor, nurses, and staff often do not have time to carefully isolate biologically contaminated materials in conventional storage containers, which are sometimes impractical in this setting for several reasons. The top of such containers must be open-faced so that contaminated materials may be quickly and easily placed into them. However, because the attending personnel are generally moving quickly, they do not have time to carefully place the materials in the bin. Instead, at best, the materials are hastily dropped into the bin, which causes the materials to come into contact with the lip or rim of the container, contaminating it with the very biological material that the container is meant to sequester.
Once the container itself is contaminated, it ceases to serve its purpose unless thoroughly cleaned and sanitized, which costs time and money, assuming it is done at all. If the technicians or other staff responsible for cleaning the operating room neglect to clean the bin, the contaminated container will be used again with the next patient, exposing that patient— and the attending staff— to biological materials from the last patient, thus increasing the risk of infection and disease to both staff and future patients using the operating room.
Ordinarily, this problem would be solved by lining the disposal bin with a flexible liner, such as a sterilized plastic bag. The bag is placed in the bin and the open end of the bag is inverted to cover the rim of the storage bin, similar to a typical residential kitchen trash can. Thus, when biologically contaminated products are deposited in the waste disposal bin, even if some of the biological material comes into contact with the rim, the rim is covered by the plastic bag. When the bag is removed from the bin and sealed, the portion of the bag that was exposed to the contaminated material will be within in the interior of the bag, sequestering the contaminated materials.
However, this solution also presents its own set of problems. First, when a liner bag is placed over the rim, pockets of air generally remain in the bin between the interior surface of the bin and the exterior surface of the bag. When materials are discarded into the bin, the volume of the materials displaces some of the trapped air. Because materials are typically dropped into the bin, this displacement is usually very rapid. Because the containers are typically enclosed except for the central opening, the only major route for the displaced air to flow through is between the exterior of the bag and interior of the bin, ultimately venting into the environment through the opening in the bin by passing between the bag and the rim.
Because the material discarded rapidly displaces the air, the air in turn rapidly ventilates, often dislodging the bag from the rim, which slips partially or completely into the interior of the bin. This then leaves the rim exposed when the next item is discarded, and the doctors and nurses often cannot and should not pause mid-procedure to reattach the bag. The problem is thus worse— not only is the bin exposed to contamination, but the bag that has fallen into the container is also exposed and the exterior of the bag may become contaminated. The staff then must not only safely dispose of the biological material in the container, but also must dispose of the contaminated bag.
This problem might be addressed by fitting a smaller bag to the container so that the fit between the bag and rim is snug, preventing the bag from slipping into the container. However, this only substitutes one problem for another. The tighter fit generally cuts off the primary ventilation route for trapped air. When material is thrown into such a bag, the displaced air is trapped with no escape route, and the total volume available for the air decreases with each item that is thrown into the bin. This places the air under increasing pressure, forcing it to relocate to the area of the bin where it can most expand to equalize pressure with the air in the environment. Because the material in the bag accumulates at the bottom of the bin, the trapped air generally accumulates near the top of the bin, exerting increasing pressure on the exterior of the bag, causing it to collapse and “puff in” from the perception of the user.
As material accumulates in the container, the volume available for the trapped air to occupy decreases and the air pressure on the exterior of the bag increases, further exaggerating the “puffing in” phenomenon. Eventually, the air pressure will either cause the bag to pop or force it off the rim, despite the tighter connection. Either situation re-introduces the problems the bag was meant to solve, as well as the problem of removing a soiled bag. The puffing effect also reduces the amount of available volume within the bag, causing the container to appear “full” even though there is unused storage volume within the bin occupied by the trapped air.
Further, the smaller bag stretched over the rim to achieve a tighter seal is under increased stress, weakening the bag and increasing the risk of a tear, particularly as objects with edges—even blunt edges— are thrown into the container. For example, where the bin is used to hold materials such as a surgical clamp, if a clamp is even gently dropped into the storage bin and impacts the rim, the thinly stretched plastic bag will be caught in the impact between the clamp and the rim. Because the smaller bag is more tightly stretched, the likelihood of the bag tearing in this impact is higher. If the bag tears, the rim of the container is once again exposed to contamination and the bag itself is no longer self-contained when closed. Thus, the entire system doesn't work, as the container becomes contaminated despite the bag, and the ripped bag is no longer effective at sequestering the contaminated tools or materials stored within it. Similarly, the puffing effect stretches the portion of the bag within the interior of the container, providing an increased surface area to contact discarded materials and giving the bag less flexibility to yield as discarded materials descend into the bin. This in turn also increases the risk of rips or tears in the bag.
This problem might be partially solved by including a shield or grommet which both holds the bag in place around the rim and protects it from being torn by discarded materials impacting the rim. However, this fails to address the problems caused by trapped air and introduces yet further problems. Instead of a contaminated rim that must be re-sterilized and sanitized before each use, the grommet must be sterilized or replaced. Further, to remove the bag from the container, the grommet first must be removed and set aside. If the contaminated grommet is placed on another surface, that surface may become contaminated and require cleaning and sterilization as well. In the fast-paced environment of a medical services facility, there exists a reasonable likelihood that the staff cleaning the room will not appreciate, or simply overlook, that this surface is now contaminated and must be re-sterilized, thus re-introducing the problem of exposing the next patient to contaminated materials from a prior patient. Also, by temporarily placing the grommet somewhere else, there is a risk that the grommet will be forgotten in the haste to clean and sterilize the room, thus leaving a contaminated item in the room, and re-introducing the very risk of infection and disease that the bin is meant to reduce.